In recent years, introduction of a distributed power source is ongoing in a consumer's facility which uses grid power. The distributed power source includes, for example, a power generation apparatus such as a photovoltaic cell and a fuel cell, and a storage battery.
While the output of the distributed power source (the photovoltaic cell, the fuel cell, and the storage battery) is DC power, the grid power is AC power. For this reason, a load supplied with the power from the grid is also configured to correspond to the specification of the AC power. Therefore, there is known a power conversion apparatus which converts the output of the distributed power source into the AC power and supplies the AC power to the grid and/or the load. The power conversion apparatus includes a DC/AC converter which converts the DC power into the AC power.
In a case where the power conversion apparatus is in a connected state with the grid, the power conversion apparatus converts the output of the distributed power source into the AC power, and outputs the AC power to a distribution board, so as to supply the power to the grid and/or the load. Such an operation of the power conversion apparatus is called a connected operation.
Alternatively, in a case where the power conversion apparatus is in a disconnected state with the grid due to blackout or the like of the grid, the power conversion apparatus converts the output of the distributed power source into the AC power, and outputs the AC power to a self-sustained operation outlet or the like, so as to supply the power to the load. Such an operation of the power conversion apparatus is called a self-sustained operation.
In addition, there is known a hybrid power conversion apparatus which can be used for both of the power generation apparatus (for example, the photovoltaic cell) and the storage battery. The hybrid power conversion apparatus supplies the outputs of the power generation apparatus and the storage battery to the grid and/or the load, so as to perform the connected operation or the self-sustained operation. In addition, the hybrid power conversion apparatus supplies the output of the power generation apparatus as the DC power to the storage battery, so as to charge the storage battery (for example, Patent Literature 1).